CAT3604 Datasheet, PDF (5/11 Pages) Catalyst Semiconductor – 4-Channel Regulated Charge Pump White LED Driver

CAT3604
LED CURRENT SETTING
The LED current is set by the external resistor R_SET
connected between the RSET pin and ground.
Table 1 lists various LED currents and the associ-
ated R_SET resistor value for standard 1% precision
surface mount resistors.
LED Current (mA)
1
2
5
10
15
20
30
R_SET (kΩ)
649
287
102
49.9
32.4
23.7
15.4
SHORT CIRCUIT DETECT/DISABLE
The unused LED channels can also be turned off by
connecting the respective LED pins to VOUT. In
which case, the corresponding LED driver is disabled
and the typical LED sink current is only about 20µA.
When the following equation is true on any channel,
the driver turns off the LED channel:
VOUT - V_LED ≤ 1V (LED channel OFF)
Note: The CAT3604 is designed to drive LEDs with
forward voltage greater than 1V and is not compatible
with resistive loads.
Table 1. RSET Resistor Selection
The digital control lines CTR0, CTR1 adn CTR2
allow to turn On or Off a combition of LEDs as
shown in Table 2.
CTR2
0
0
0
0
1
1
1
1
Control Lines
CTR1
0
0
1
1
0
0
1
1
Notes: 1 = logic high (or VIN)
0 = logic low (or GND)
- = LED output OFF
CTR0
0
1
0
1
0
1
0
1
LED4
-
-
-
ON
-
-
ON
-
LED Outputs
LED3
LED2
-
-
-
ON
ON
-
-
-
-
ON
ON
ON
ON
ON
-
-
Table 2: LED Selection
LED1
ON
-
-
-
ON
ON
ON
-
© 2005 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. 5008, Rev. I